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Old Feb 25, 2004, 12:36 PM
resistance is futile!
Tanis's Avatar
Essen, Germany
Joined Jan 2004
363 Posts
Here is a modified pic of the PCB.



For a full modification of the board, the red transistors should be replaced by 'IRLML 2502' (N-FET) and the blue ones should be changed to 'IRLML 6401' (P-FET).
I would suggest, only to change the transistor No. 6 and make a link where i draw the light blue bar. To leave transistor No. 5 as is, saves weight, as you don't have to use a 'Cruse-Resistor' (Ri of the original transistor is high enough )
I think it's not necessary to modify the H-Bridge for the actuator, cause there should not flow much current (depends on coil-resitance).
I have to check out F1 an F2 function of te RX6 C chip... that'll take a while... sorry about that...

PS: I've never used an actuator on the 'pulsed' H-Bridge (non-turbo-mode), but i guess you would have a 2 step digital steering...

PSS: If the H-Bridge is tuned with IRLML 2502 and IRLML 6401, the PCB need's at least 2,4 V !!!!
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Last edited by Tanis; Feb 25, 2004 at 12:39 PM.
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Old Feb 25, 2004, 05:48 PM
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Netherlands
Joined Feb 2004
442 Posts
Tanis,
thank you so very much..
But what is the "F1"and the "F2"function?
And you sad:" for al FULL modification,you need to replace all the transistors" "i would suggest to..."
So is it better to change all of them,or only number 6?
(I fly withe a 145mah kokam,so thats not the problem for the 2.4V that he need )
And the H-bridge,im sorry,but that is....¿
Tommorow I call every local shop,near this city,and if the dont have de fets,i must order them of the internet so that's take a little wile..
So,when i replace transitor 6,the moter gets to see the full battery voltage..
(ofcourse i must turn the signals of the transmitter)..
(people thank you very much for the time hou spend om my questions..)
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Old Feb 25, 2004, 11:55 PM
resistance is futile!
Tanis's Avatar
Essen, Germany
Joined Jan 2004
363 Posts
@Remy
Check your PM, so you can save some calls !
The F1 and F2 functions are like a '3rd chanel', unfortunally not used in most PCB-designs, so you have to pick the signal directly from the RX6 C chip and build the 'driving-part' externally. My english is'nt very good, and it's hard for me to describe my thoughts....
As i said, you should first change only the transistor No.6, and try if it works. If the actuator has not enough power, you can cange the transistors No.1 - No.4, but i guess that is not necessary.

With a single transitor you can only drive a motor or an actuator in one direction. If you need to have 2 directions, you have to use an H-Bridge. Try to google it out (i'm to lazy to describe that in english... ).

I'm completely new to RC-Planes / Helicopters, but i've done lots of Bit Char G mod's ...

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Old Feb 26, 2004, 04:26 AM
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Brussels,Belgium
Joined Feb 2000
81 Posts
to Tanis

Do you know where I can find Fets like FDS6679 (13 A P channel )

I've tried to buy here in belgium , but no luck

I only need some (not many ) for a repair .

you can reply in German

Gruß

Koen VG
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Old Feb 26, 2004, 04:52 AM
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Netherlands
Joined Feb 2004
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Tanis,i have send you a PM reply back
The H-bridge,i have searched on the internet(www.google.nl) I only found that a H-bridge isa sort of IC..
By the way,you do it greet with your english
its better than the mine
tanis,thank you very much for you time,en when i have the fets,soldered them,en tryed them,i let immideatly know it
Weight a second,ow here!,I have found the answer,to the H-bridge:P
http://www.interaccess.org/arg/arg-list/msg00560.html

Met vriendelijke groeten (this is dutch for"With frendly greets" "
("mit friendlich grüten")
Remy van Wijk
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Old Feb 26, 2004, 05:52 AM
resistance is futile!
Tanis's Avatar
Essen, Germany
Joined Jan 2004
363 Posts
@Koen Van Goethem
i don't know where to get the FDS6679 by now, but i've found a similar Fet, that is easier to get : its the 'irf7416 smd'. This Fet is pincomatible to the FDS6679, but only can handle 10 amps. I have to check several Datasheets, when i'm back from work, maybe there is a better matching Fet....

Regards

--- Tanis ---

PS: I've answered in (bad?) english, cause others like to know it too...
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Old Mar 01, 2004, 01:32 AM
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Brussels,Belgium
Joined Feb 2000
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to remis : if you like to learn about H-bridge
read the following link

http://www.dprg.org/tutorials/1998-04a/

make shure you read up to the part "Semiconductor H-Bridges"

this is what we need to power an E motor is the 2 directions .

in modern circuits , the NPN and PNP transistors are replaced by
N- and P-Fets .


To Tanis : Your english is "VERY" good , my german is worse .
I really need the same Fets , they are used in a 3phase H bridge
one phase has burned out
I'm not shure weather I will get my hands on these specific fets

regards ,

Koen VG
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Old Mar 01, 2004, 02:09 AM
resistance is futile!
Tanis's Avatar
Essen, Germany
Joined Jan 2004
363 Posts
@Koen Van Goethem

i'll ask the a college at work, if he could get some 'samples' of that Fet. That may take a while, but they are for free then ...

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Old Mar 01, 2004, 05:05 AM
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Brussels,Belgium
Joined Feb 2000
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Tanis , that would be great !! Costs will been paid .

This FDS6679 Fet is used together with an N channel IRF7831

can your collegue check for this too ??

best regards ,

Koen VG
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Old Mar 01, 2004, 05:53 AM
resistance is futile!
Tanis's Avatar
Essen, Germany
Joined Jan 2004
363 Posts
@Koen Van Goethem

the IRF7831 is aviable at www.conrad.de (Artikel-Nr.: 164357 - 14 ). The price is 1,91 €.... But i will ask the college too ...

regards

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Old Mar 01, 2004, 08:52 AM
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Brussels,Belgium
Joined Feb 2000
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What a response time !!

good to know that conrad can deliver the IRF Fet

regards ,

Koen VG
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Old Mar 21, 2004, 12:53 AM
Wonder bread
theoneinventor's Avatar
USA washington
Joined Mar 2004
17 Posts
the link called bit char-g hack madness; the first post, doesn't work i really want to ckeck out that site though. what to do?
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Old Mar 22, 2004, 09:46 AM
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USA
Joined Oct 2001
5,174 Posts
The link will work within a day or so. The RC-CAM site's host is having hardware issues. I understand that the server is being rebuilt due to hard drive issues.

RC-CAM
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Last edited by Mr.RC-CAM; Mar 22, 2004 at 10:59 AM.
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